Block copolymers containing polysiloxane segments and polyoxyalkylene segments are widely used as surface active agents in coatings, urethane foams, plastics, textiles and printing processes, to name only a few applications. Specifically, the silicone compounds are composed of a siloxane backbone with polyalkylene oxide pendants. Members of this class, when dissolved in water, achieve low surface tension values (as low as 20 dynes/cm.), an ability only exceeded by fluorocarbon surfactants.
Fluorochemical surfactant compounds are the most effective surface active agents known, reducing the surface tension of water to as low as 15 dynes/cm. The unique surface activity of fluorosurfactants is attributed to the ability of the perfluoroalkyl groups to pack at the air-water interface.
Fluorochemical surfactants, however, are quite costly at $20-50/lb compared to the silicone surfactants which are available at about $5/lb. For this reason, fluorosurfactants are prohibitively used in applications that require surface active agents.
In this invention, we have developed a new class of surfactants containing both silicone and perfluoroalkyl groups. We have shown improvement in surface active properties of alkoxylated siloxanes by modification of the alkylene oxide pendants with perfluoroalkyl containing groups. These novel perfluoroalkyl modified silicones exhibit greater surface activity i.e. lower surface tension, than the parent siloxane, even at 10% of the concentration. As a result, they improve or impart properties such as wetting, penetration, spreading, levelling, foam stability, flow properties, dispersion properties and oil and water repellency. Their cost is competitive with the silicone surfactants since only a small amount of a perfluoroalkyl moiety is required to improve surface properties and since the use level required to obtain similar performance is greatly reduced.